Electric generator or motor.



No. 894,329; I PATENTED JULY 28, 1908."

- C(LKENNEDYf ELECTRIC GENERATOR 0R MOTOR.

APPLICATION FILED JULY 29,1905.

2 SHEETS-SHEET l.

' WITNESSES 11v VLA) TOR .No. 894,329 I PATENTED JULY 28, 1908..

' 0. L. KENNEDY.

.ELBGT'RIG GENERATOR'OR MOTOR APPLICATION FILED JULY 29, 1905.

2 SHEETS-SHEET 2.

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CARLTON L. KENNEDKOF BRAINTREE. MASSACHUSETTS.

nrincrnrc GENERATOR on MOTOR.

Specification of Letters Patent.

Patented July 28, 1908.

Application filed July 29, 1505. Serial No. 271,807.

T 0 all whom it may concern:

Be it known that I, CARLTON L. KENNEDY, a resident of Braintree, in the county of Norfolk and State of Massachusetts, have invented certain new and useful Improvements in Electric Generators or Motors and I do hereby declare the following to be a full, clear, and exact description of the invention,

such as will enable others skilled in the art to which it appertains to make and use the same-..

My invention'relates to improvements in continuous current electric generators and motors, an object of the invention being to construct the machine in such manner that it can be operated as amulti-speed motor, or as a multi-voltage generator or as a motorgenerator driven by an outside source of current and generating currents of different voltages.

A further object is to provide such a machine with simple and efficient means for preventing sparking at the brushes.

' brushes arranged as in Fig. 1.

In the accompanying drawings: Figure 1 is a diagrammatical 'view showing an embodi-rnent of my invention; Figs. 2 and 3 show other arrangements of brushes: Fig. 4 is a diagram showing external circuits with Figs. 5 and 6 are diagrams showing external circuits with brushes arranged as shown in Figs. 2 and 3. Figs. 7 and 8 are views showing modifications.

For the sake of convenience and SlIH- plicity in illustrating my invention, I have shown dia ramm'atically, in Fig. 1,- a bipolar macl 'iine although my invention -is equally Well adaptable to a dynamo or motor of the multipolar type. The pole. pieces of the respective field magnets are shown at N. S. and between these, the armature A is located. This armature maybe of the ring type having closed coils, or a drum armature may be used. The commutator is shown at C and its segments are connected with the armature coils in a manner which is well un taken, as will be-herei'nafter more fully explained. In Fig. 1, I have shown two such auxiliar brushes 2, 3. Assuming that the total voltage generated by the machine is 240, the voltage in the external circuit ,between the brushes 2 and 3 will be 60, and between the brushes 1 and 2, and 3 and 4 the voltage will be 90-. It is apparent then, that with the use ofthe auxiliary brushes 2 and 3, arranged with respect to the commutator brushes 14, as .--hown in Fig. 1. 90 and 240 volt currents may be obtamed. It Will 8 180 beobserved that 150 volt current can be, obtained between the brushes 1 andS or 2 and 4t.

Assume now that instead-of operating the machine as a dynamo, it be run as a motor. Current of the proper voltage being supplied to the brushes 14, the machine will operate as a bi-polar motor, standard in every respect. If however, the current be supplied to the auxiliary brushes 2-3, it will be readily seen' that but one-fourth of the conductors on that side of the armature will be active, and that therefore, in order to generate the proper counter electro-motiveforce,- the armature will run four times faster than when the current was supplied to the brushes 1-4. Similarly, current supplied to brushes 1'3, will cause the armature to run about 1.6 faster than at first, and if the current be supplied at brushes 12, the motor will run approximately 2.5 faster. Thus, by ;making proper combinations of brushes. in connecting the motor. in circuit with the source of electricalenergy, the speedof the, motor'may be varied in about the proportions of 1: 1.6: 2.514.; By using field variation in the usual manner, speed may be obtained between these ratios.

Experience has shown that the average resistance between brushes 2 and, 3, when arranged as "shown in Figs-'1, is about one-third that betweenthe commutator brushes'l 4. Thereforejfwhen the increased radiation, se cured at-high speed is considered,- it will readily be seen that theoutput on the highest speed. That is to say; the power developed varies about as the square root of the speed.

By using one, two, three or more auxiliary speed is about doublejthat on the lowest brushes on the commutatofiand by placing them at other positions than shown at 2-;3,

Fig. 1, many other combinations may "he formed. Some of these are shown in F igsfiQ and 3. Fig. 2 shows the commutator of a lei-polar armature around which brushes are grouped to give six voltages when the mahine is run as a dynamo,viz. (50-80- 110-14l)19()-250 volts. When used as a motor, speeds would be obtained in about the following proportions; 1; 1.3; 1.8; 2.-l; 3.2 4.1.

\Yhen, as shown in Fig. 3, only one auxiliary brush is placed at 2, dividing the armature into two equal sections, the machine may be used as a three-wire genera tor, as a motor balanced for a three-wire circuit, or as a two-speed motor.

In the arrangement shown in Fig. 1, auxiliary brushes may be placed on the commutater at points o, b, ant connected in parallel respectively with brushes 2 and 3.

The arrangements of auxiliary brushes hereinbefore described are not limited to bipolar machines, since the sameprinciple may be utilized in a 1n ultipolar machine by supplyin; as many sets of brushes as there are pairs of poles. With a multi polar armature wound with the so-callcd wave winding but one set of brushes is necessary although more may be used if desired.

When a machine arranged as shown in, Fig. 2, is used as a motor, by applying a 250 volt current to brushes 1 and 1, current may be taken from the auxiliary brushes in the same manner as though it were driven by an outside source of mechanical power. he machine then becomes a multi-voltage motorgenerator, giving voltages of 60, 80, 1 1t). 24o, 190 and 256. If the current be supplied to brushes 1 and 2, the voltages obtaimtble will be 250; 4220, 140, 560, 760, 1000. Similarly, other voltages may be obtained by supplying the primary current to other brushes. 'lhe same plan may be pursued with the arrangements shown in Figs. 1 and 3 or any other combination.

It is a fact Well understood that in order to secure good commutation in. a continuous current generator, all the brushes which are carrying; current should be placed on a ncu tral spot on the commutator;-that is to say, a spot on the commutator where a brush may be placed without short-circuiting a coil which is cutting lines or force. Thus, in Fig. 1, brushes 1 and. 4 are on neutral spots if the bars on which they rest are connected to coils occupyingthe positions c and (Z on the armature core. In the ordinary generator or niotor however, the positions of the auxiliary brushes in Fig. 1. would not be neutral points, and if brushes were laced, on these spots, sparking would occur. It is therefore important, when brushes are placed on. the commutator at points other than at the neutral spots, to. provide some means ol eliminating sparking. This may be done in several ways, viz: by increasing the resistance of the coil or coils un ergoing commutation, and. so

limiting the current which may be induced in them while they are short-circuited by the brush; or by providing artificial neiural points on the commutator at the positions where it is desired to place brushes; or by a combination of these me thou's.

Theiirst plan,--that of increasing the resistance oi the short circuitecl coil, may be accomplished by using high resistance leads to connect the commutator to the WlIILllllf-J'. instead of connecting the sub--divi;-;ions of a closed coil winding directly to the commutator in the usual manner, they are connected through wires or strips of comparatively high resistance. Then, since the armature is slwrt-circuited upon itse'l any o'l these high resistance strips will be carrying; current only when the conmlutator bar to which it is connected is carrying current, or is under a brush, and it will be carrying no current when the. commutator bar to which it is con nected is out out of circuit by passing from under the brush. Thereiore, these resistance leads, which carry current but a small part oi the time, may be made smalland ol' high resistance without greatly all'ect the heating or the regulation of the armature.

The second. method, that of producing artilicial neutral points on the connnutator, may be carried out by cutting slots in the pole pieces of the lield magnets at the desired points in an axial direction. in F155. 1 oi the drawing 1 have shown each pol pie e having two s.ots 5, .5, each having a cross section approximately elliptical. The lines of force from the pole pieces 'will then pass into the armature at those places where the iron ol' the pole piece closely approach s the armature, while the large air s ices will comparative y free from them.

ii the armature ring wound," it only be necessary to cut away the pole pie at 5", .in order to place brush on the com: mutator. ll the armature is drum wound both pole pieces must be slotted. at points opposite one another, since each coil 01' a drum armature is laid upon the armature surface at two diametricallj =L ppos1te points. While the above method will produce approximately neutral spots upon theconunutater, it will be found that it the air spaces formed bv the slots in the pole p small as not to u milulj. increase the size oi the field structure, a small m'unber oi lines ol force will leak through these air spaces, and will enter the armature. it absolutely neutral points are desired at the slots, these straw lines cl lore-e must be '{)3- .'(I )t((l from en innthe armature. I therefore place bars e, 7, g, I, in the 'a A h ps formed 1 slots, close to the armature id para its axis. The bars -o.n..- i(lcr.=rhlonger than Jhc rial catheters of the pieces and each end o l abo t connected to the one 11 position under the other pole piece, by iron connecting bars 01, j, which are well clear of both pole pieces and the armature. Thus any stray lines of force emanating from pole piece 5 md crossing an air-gap,will not reach the armature, but will pass into a bar (as e) which protects the armature along its full length. They will then pass through a connecting bar (as i) to the corresponding bar as g) in a groove or air-gap in the pole piece N and enter said pole piece. Thus, brushes 2 and 3 will be set upon the (ommutator at almost absolutely neutral points and no difficulty will be encountered withcommutation.

The stray lines of force at the slotted portions of the pole pieces, opposite which it may be desired to place brushes, may also be overcome by displacing the iron bars c, f, g, h, with coils l..- of fine wire inserted in the slots or air-gaps, said coils being connected, either directly across the line, or in series with the shunt field coils (Fig. 8). If these coils be wound so as to oppose the field, and be corrcctl y proportioned, they will eiiectually oppose the passage of any stray lines of force. These coils might be wound with heavy wire and eachone connected in series with the brush under it (Fig. 7 The magnetic efi'cct will be proportional to the current flowing through the brush and may be made ol the right polarity to provide a positive field for commutation, the strength of which will vary with the current passing through the brush.

Having fully described my invention, what I claim as new and desire to secure by Letters-Patent is l. A continuous current dynamo or motor having a slot in the face of each pole piece, means for shunting magnetic lines of force around the armature from the slotted por tions of the pole pieces and'one or more auxiliary brushes upon the commutator on the neutral spots formed by said slots, the slots and brushes being so spaced that the vol- Lagos generated under the two adjacent sec tions of one pole face formed by the slot therein, are unequal.

2. A continuous current dynamo or motor having a slotted pole piece, one or more auxiliary brushes upon the commutator on the neutral points formed by the slots of the pole piece, an iron bar in each slot of the pole piece and a conductor for lines of force shunting the armature and connectedwith each of said irou bars.

3. A continuous current dynamo or motor having a slotted pole piece, auxiliary brushes upon the commutator on the neutral points formed by the slots in the pole piece an iron bar in each of said slots, and an iron bar connevi iug each of the iron bars in the slots-with another part ol the magnetic circuit.

4. A continuoi-is cnr'ont dynamo or motor having a slot in the face of each pole piece and one or more auxiliary brushes upon the commutator on the neutral spots formed by said slots, the brushes being so placed upon one half of the commutatoronly as to avoid local cross currents in the armature, substantial-ly as illustrated and described.

5. A continuous current dynamo or motor commutator on the neutral spots formed by,

said slots, the brushes being so placed on one hall of the commutator only and so connected as to avold local cross currents 1n the armature and the slots and brushes so spaced that the voltagesgenerated under the two adjacent sections formed in one pole face by said slots are unequal.

7'. A continuous current dynamo or motor having two or more slots in the faceof each pole piece and two or more auxiliary brushes upon the commutatoron the neutral spots formed by said slots, the brushes being so placed on one side of the commutator only and so connected as to avoid local cross currents in the armature, and the slots and brushes being so s aced that the voltages generated under at east two of the adjacent sections in one pole face formed by said slots, are unequal.

8. A continuous curient dynamo or motor havinga slot in the face of each pole piece and one or more auxiliary brushes upon one side only of the commutator on the neutral spots formed by said slots, the brushes being so placed and connected as to avoid local cross currents in the armature, and the slotsand brushes being so spaced that different vol-' tages generated may be combined to form approximately an increasing or decreasing progression.

9. A continuous current dynamo or motor having two or more slots in the face of each pole piece and two or more auxiliary brushes upon the commutator on the neutral spots formed by said slots, the brushes being so placed on one side only of the commutator and so connected asto avoid local cross currents in the armature, and slots andbrushcs being so spaced that the difi'erent voltages generated maybe combined to form approximately a regularly increasing or decreasing progression.

10. A continuous current dynamo or 1110- tor having one or more slots in the face of each pole piece, one or more auxiliary brushes upon the conunutator on the neutral spots formed by said slots, an iron bar in each slot ton having one or more slots in the face of and iron bars connecting the bars in the slots of one pole piece with the bars in the slots of another pole piece.

11. A continuous current dynamo or m0- tor having one or more slots in the face of each pole piece, one or more auxiliary brushes upon the commutator on the neutral spots formed by said slots, an iron bar in each slot, iron bars connecting the bars in the slots in one pole piece with the bars in the slots of another pole piece, the brushes being so placed and connected as to avoid local cross currents in the armature, and the slots and brushes being so spaced that the different Voltages generated may be combined to form ap proximately a regular increasing or decreasing progression. 4

12 A continuous current dynamo or moeach pole piece, one ormore auxiliary brushes upon the commutator oh the neutral spotsformed by said slots, a conductor in each slot,

said conductors being so connected as to oppose leakage of the magnetic flux due to main field coils, through said slots and into the armature. i

13. A continuous current dynamo or motor having one or more slots in the face'o'f each pole p ece, one or more auxiliary brushes upon the commutator on the neutral spots formed by said slots, a conductor in each slot,

said conductors being so connected as to oppose the leaka e of the magnetic flux dueto the main fiel through said slots and into the armature, the aforesaid brushes being so placed and connected as to avoid local cross currents in the armature, and the slots and brushes being so spaced that the different voltages generated may be combined to form approximately a regularly increasing or de creasing progression.

14. A continuous current generator or motor having a slot in each pole piece, an auxiliary brush on the commutator on the neutral point formed by said slots, an iron bar in the slot of each ole piece, and an iron bar connecting the Ear in the slot of one pole piece with the bar in the slot of the other pole piece.

15. A generator or motor having two or more slots in the face of each pole piece, auxil iary brushes on the commutator on the 118L- tral points formed by said slots, an iron bar in each slot, and iron bars connecting the bars in the slots in one pole piece with the bars in the slots of the other pole piece to divert lines of force around the armature.

In testimony whereof, I have signed this specification in the presence of two subscribing itnesses.

CARLTON L. KENNEDY.

Witnesses:

PERLEY E. BAnnoUn,

JOHN BARBOUR. 

